Thermostatic-control mechanism for domestic refrigerating systems



20, 1929- D. D. PARSHALL 1,725,415

THERMOSTATIC. CONTROL MECHANISM FOR DOMESTIC REFRIGERATING SYSTEMS Filed May 11, 1925 INVENTOR i aufl WM ATTORNEY Patented Aug. 20, 1929.

UNITED STATES PATENT OFFICE.

DALLAS D. PARSH ALL, OF WATER-VLIET, NEW YORK, ASSIGNOR TO THE JACK FROST COMPANY, OF STAMFORD, CONNECTICUT, A CORPORATION OF DELAWARE.

THERMOSTATIC-CONTROL MECHANISM FOR DOMESTIC REFRIGERATING SYSTEMS.

Application filed May 11,

The general object of my present invention is to provide an improved form of control mechanism automatically responsive to ten'iperature, suitable for use in controlling the circulating motor of a mechanical refrigeration system, and primarily devised, and especially adapted for use in domestic refrigerating systems. More specifically, the object of my invention is to provide a thermostatically actuated motor control switch characterized by its simplicity,

strength, ruggedness and by its effectiveness for its intended purposes.

The various features'of novelty which characterize my invention are pointed out with particularity in the claims annexed to and forming a part of this specification; but for a better understanding of the invention, however, its advantages and specific objects attained with its use, reference should be had to the accompanying drawings and' descriptive matter in which I have illustrated and described the best forms of my invention.

Of the drawings:

Fig. 1 is a-diagrammatic elevation of a refrigeration system in which my invention is incorporated;

Fig. 2 is a vertical section through the thermostatic control switch;

Fig. 3 is a section on the line 3-3 of Fig. 2; and

Flfig. 4 is a section on the line H of In the drawings, I have illustrated the use of my invention in a refrigerating system comprising a cooling reservoir or expansion chamber A adapted for insertion in an ice box or refrigerator for domestic use, receiving a liquid heat absorbing fluid or refrigerant from a condenser B through a gipeC containing a pressure reducing valve A circulating pump E withdraws the vaporized cooling fluid from the cooling reservoir A through a conduit F and after compressing the vapor discharges it into the air cooled condenser B. i

My present invention is concerned with the construction and arrangement of means for automatically controlling the operation of the motor G which is operatively connected to the circulating pump E, in response to temperature requirements, and comprises the thermostatic switch mechanism shown in Figs. 2, 3, and 4 of the draw- 56 ing. This mechanism includes a thermo- 1925. Serial No. 29,271.

stat which in the preferred construction illustrated comprises a cast metal cup-shaped member H.

As shown, the member H rests on top of the expansion chamber A between centering lugs A on the top wall of the latter and is secured in place by set screws A passing through the lugs.

The upper end of the chamber space H in the member H is closed by a cylindrical bellows element J which partially fills the space H and has a closed lower end J and an out-turned flange J 2 at its upper end. The flange J 2 is clamped between the rim or upperedge H of the member H, and a clamping plate or head K secured to the member H by screws or bolts K. L represents a gasket provided to insure a tight joint. An opening H formed in the bottom wall of the chamber space H and normally closed by a screw plug H, is providedfor charging the space H with a suitable-volatile fluid such as S0,.

The head K is formed with a downwardly extending cylindrical boss K forming a tubular guide for stem J secured at its lower end to the lower end J of the bellows element J. The stem J 3 which extends above the head K is connected above the latter to a control switch M in such manner that when the S0 in the space H expands on an increase in temperature, and collapses the bellows J and thereby moves the stem J 3 upwardly, the switch M closes a motor energizing circuit and starts the motor G into operation. When the" resultant expansion of the refrigerant in the chamber A effects a sufiicient lowering of the temperature of the S0 in the chamber H, the consequent expansion of the bellows element J actuates the switch M to open the previously closed motor circuit, thereby stopping the motor G and the circulation of the refrigerant. The expansion of the bellows element J when the vapor pressure in the chamber H is reduced is due in part to atmospheric pressure on the upper side of the element, and in part of the action of a helical spring 0. The latter surrounds the tubular guide K with its lower end abuttin the closed end J of the bellows element and with its upper end abutting a nut P threaded on the guide K By adjusting the nut P on the threaded guide K it is thus possible to regulate the tension of the spring so as to require a greater or lesser pressure of the S0 in order to collapse the bellows element J. As shown the nut P is formed with notches in its periphery to facilitate its rotation by suitable implement inserted through a slot K in the head 5K.

The motor controlling switch M comprises a mercury containing tube clamped in a support Q which comprises a horizontal shaft portion Q journalled in a'bossK" formed the head K by means of a pair of pins K and K anchored in the side walls of a slot formed in an integral upstanding lug K on the head K. One end of the lever H extends into the last mentioned slot-with its upper edge engaged by the pin K and its lower edge engaged by the pin K. The opposite end of the lever B extends between upper and lower pins or projections Q and Q carried by the member Q and extending transversely tothe shaft Q.

clomd is simple, efiective, durable,

The switch M and the connections through which it is operated by the bellows stem J are enclosed by a casing formed in part by thehead K, in part by a bracket like extension H of the body H, and in part by a cover S detachably'connected to the head K. 4 The mercury containing tube of the switch M is provided with two contacts M and M carried by conductors extending through the wall of the tube. The contacts M and M are so disposed as to be electrically connected by the mercury in the tube when the bellows J is compressed and the tube is thereby tilted into the osition shown in Fig. 3. When the bellows d. is expanded the tube tilts into a position in which the mercury no longer connects the contacts M and M When the contacts-M and M areconnected by the mercury in theswitch tube, the motor G is energized from line conductors 1 and 2 through circuit connections including a conductor 3 running from line conductor 2 to one terminal of the motor, a conductor a running from the line conductor 1 to the contact M, and a conductor 5 the contact M motor G.

The thermostatic control mechanism disy and pract cally fool-proof as is desirable for its intended use in domestic refrigeration systems. The manner in which the lever is pivotall connected to the stem J and to the head K tends to prevent objectionable lateral play of the lever B while at the same time permittlng of a certain amount'of lost motion running from to the second terminal of the which contributes to a quick and positive make and break of the mercury connection between the contacts M and M The switch tube proper forms a relatively inexpensive, durable, and reliable form of switch which can easily be replaced when replacement is necessary. The thick walls of the thermostat casing H tend to an efficient and accurate control of the refrigerator temperature, by permitting the thermostaticelement to respond to gradual changes in the refrigera tor temperature, while protecting the ther- Inostatic element against the immediate effect of sudden and momentary changes in the refrigerator temperature such as are caused by the occasional and temporary opening of the door of the refrigerator in which my improvement is incorporated. The thick walls of the thermostatic casing H and the cover S form a strong and rugged housing for the more delicate operating parts of the thermostatic mechanism which is especially desirablefor domestic service with unskilled attendance because it minimizes the danger of accidental breakage of, or injury tothe mechanism.

I claim 1. A thermostatic regulator comprising in combination a casing having a removable part, a flexible thermostatic element mounted in said casing, a switch actuator connected to said element and extending through said removable casing part, and a lever mounted on said removable casing part and engaged by said actuator, a rocking element journalled on said casing part and connect ed to said lever to be oscillated by said actuator and a switch tube mounted on said rocking element, internal contacts carried by said tube, and a body of mercury connecting said contacts in one position but not in another of the positions into which the -tube is turned by the oscillation of said lever.

2. A. thermostatic regulator comprising a cup-shaped casing, a casing head secured to the casing body and formed at its underside with an externally threaded hollow boss, a cup-shaped bellows element mounted in said cas ng and comprising an out-turned flange at its upper end clamped between the easmg and head and uniting with the casing body to form an expansible collapsible chamber space for a volatile thermostatic element, a switch actuator slidingly received in said boss and secured at its lower end to said bellows, a nut threaded on said boss, a spring compressed between said nut and the bottom wall of said bellows, said head being slotted to permit adjustment of said y nut, and a switch mechanism mounted on said head and connected said switch actuator.

53. A thermostatic regulator com rising a cup-shaped casing, a removable ead for to and operated by 'closin the upper end of said casin a cup-- shape bellows element locatedwit in said casing and having an out-turned flange at its upper end clamped between said head and easing whereby a chamber for a volatile thermostatic a nt is provided between said casin and sai v bellows element, an axiall mo'va le switch actuator extendingthrough said head with its lowerhead in engagement with the bottom wall of said element, and a switch mechanism mounted on saidhead andcomprisin a lever havin a fulcrumed connection wit saidhead an engaged and oscillated by said actuator, a rock ng 'ele-. ment journalled on said head to turn about an axis generally arallel to said lever and connected to-theatter to be oscillated as the lever is oscillated, a sealed tube carried by said rocking element and partially-filled with mercury, and contacts mountedin said tube to be connected in one but not in another of the positions into which said rocking element is oscillated.

4. A thermostatic regulator comprisin in combination a cup-shaped casing, a hea v anemiadetachably secured thereto, a flexible member mounted in said casing and uniting with the latter to provide a volatile fluid containing chamber of which said member forms an expansible wall, an actuator slidingly mounted .in said head and extending through the latter and connected at its inner end to said flexible member, a lever havin' a fulcrum connection to said head and pivotally connected. to said actuator, a switch tube support pivotally mounted on said head, and

comprising parts engaging said lever whereby t e reciprocatin movements of said actuator oscillates said tube support, a tube mounted on said support, contacts supported within said tube and abody, of mercury therein connecting said tube in one position but not in anot er of the positions into which it is turned lever.

Signed at Alban', in the count of Alday of April, A. D. 1925.

DALLASDJPARSHALIL.

by the oscillations of said a bany and State 0 New York, t is 22nd 

